1st Time Setting up to my Macbook Pro

Hello, I Just downloaded the FREE Jammr program (1/22/2018) onto my old mid-2010 MacBook Pro running Mac OS 10.13.2 High Sierra. I've installed 8gb RAM and an SSDrive as well (runs fast). I set up my username password and added my profile info. Then, I set up my computer's sound preferences like this…
MacOS System Preferences>Sound>Output>Headphone Port
MacOS System Preferences>Sound>Input>Line In
Question 1) I'M ONLY TESTING JAMMR AT THIS POINT. CAN I JUST USE THE SOUNDCARD, SET UP LIKE THAT (ABOVE) IF I'M ONLY PLUGGIN IN SAY, MY GUITAR INTO A GUITAR MULTI-EFFECTS PROCESSOR PEDAL INTO THE 3.5MM INPUT JACK ON MY COMPUTER? SET UP AS Line In?? R DO I HAVE TO SET UP MY AUDIO INTERFACE?
(Note: I DO have an Audio Interface (M-Audio Profire 610) which I will use when I set it up in the other room.)
After launching Jammr for the 1st time, I entered username/password and up came a DIALOGUE BOX with a choice of 3 Public jams under the Topic column in the Dialogue Box. But, only 1 of these 3 Public Jams has Users (listed under Users column).

THANK YOU!!
ART E

artest7
1) I'M ONLY TESTING JAMMR AT THIS POINT. CAN I JUST USE THE SOUNDCARD, SET UP LIKE THAT (ABOVE) IF I'M ONLY PLUGGIN IN SAY, MY GUITAR INTO A GUITAR MULTI-EFFECTS PROCESSOR PEDAL INTO THE 3.5MM INPUT JACK ON MY COMPUTER? SET UP AS Line In?? R DO I HAVE TO SET UP MY AUDIO INTERFACE?(Note: I DO have an Audio Interface (M-Audio Profire 610) which I will use when I set it up in the other room.)

Hi artest7,
You can use the built-in soundcard but audio quality is usually much better with an audio interface. Give the built-in soundcard a try and see if it's okay. Many built-in soundcards have noisy Mic and Line-in inputs that you might find distracting.

Be sure to check jammr's sound settings in jammr | Preferences… | Audio. This is where you can select the input and output devices that jammr uses.

artest7
After launching Jammr for the 1st time, I entered username/password and up came a DIALOGUE BOX with a choice of 3 Public jams under the Topic column in the Dialogue Box. But, only 1 of these 3 Public Jams has Users (listed under Users column)

This is normal. The jammr servers keep empty public jam sessions open when other people are already playing. This way you can join an empty public jam if you decide the existing jam isn't to your taste.

Welcome to jammr!